Patent GB-995872-A (GB)
Title: Hydraulic welding press for electric resistance welding with means controlling programmed course of press in pressing cylinder
IPC: B23K11/02
Filed: 1962-04-12
Abstract: 995,872. Welding by pressure. BRATISLAVSKE ELEKTROTECHNICKE ZAVODY NARODNI PODNIK. April 12, 1962 [April 12, 1961], No. 14106/62. Heading B3R. An hydraulic electric resistance welding press comprises means for controlling the programme of four pressure stages, clamping, welding, stamping and forging or annealing, and means for controlling the welding current including two two-stage pressure governors 20, 21, connected via a distributer 19 to the ram cylinder 1, one governor 20 determining the clamping and welding pressures and having a switch 24 for controlling the supply of welding current and the other governor 21 determining the stamping and forging or annealing pressures and having a switch for adjusting the distributer so that the working pressure is released and for cutting off annealing current if such is used. The electrode 3 carried on the piston 2 in the cylinder 1 is arranged above an electrode 4 carrying the work 5, 6 and the electrodes are connected to a transformer secondary 8, the primary being connected to a source 10 via an electronic control 11. The cylinder is connected to a pump 13 and to exhaust by a distributer 12 controlled by a solenoid 17. The distributer 19 is controlled by a solenoid 22. The governors 20, 21 connected to the distributer 19 by pipes a<SP>1</SP>, b<SP>1</SP> each comprises a cone 35, Fig. 3, pressed against its seat by a spring 36 and an outlet connected to its dashpot type piston relay 23, 26. Members to close. in succession switches 24, 25 are carried on the rod of the piston in relay 23 and members to open in succession switches 27, 28 are carried on the rod of the piston in relay 26. In operation, switch 34 is closed to cause distributer 12 to be moved to allow pump 13 to supply the cylinder space 14 to lower the electrode 3. The space 14 is connected to the governor 20 and when pressure has built up to clamping pressure P 1  Fig. 6, the cone 35 lifts and allows liquid to flow to the relay 23. The lower welding pressure P 2  acting on the diameter d 2  of the piston in the governor 20 is stabilized by the governor. The switch 24 is closed after a delay t 1  to energize the control 11 which passes welding current at B. After a further delay the contacts 25 close to energize solenoid 22 and shift distributer 19 to connect governor 21 to the cylinder. When the pressure rises to stamping pressure P 3  the cone is lifted and liquid flows to relay 26, the pressure being stabilized at the lower annealing pressure P 4 . The switch 27 is opened to de-energize a relay 31 and adjust the control 11 to provide pulses of annealing current and after a further delay the switch 28 opens to de-energize the solenoid 17 and shift the distributer 12 and also to de-energize the solenoidoperated switch 32 to disconnect the control 11. Welding current is cut off at the point D, Fig. 6, by a time relay of the control 11. A similar cycle for forging after welding is described. Specifications 790,793 and 826,237 are referred to.